Simplify the following expression: $n = \dfrac{r^2 - 6r + 5}{r - 5} $
Explanation: First factor the polynomial in the numerator. $ r^2 - 6r + 5 = (r - 5)(r - 1) $ So we can rewrite the expression as: $n = \dfrac{(r - 5)(r - 1)}{r - 5} $ We can divide the numerator and denominator by $(r - 5)$ on condition that $r \neq 5$ Therefore $n = r - 1; r \neq 5$